Door lock attachment

ABSTRACT

A clamping attachment for a lock bolt thumb knob for preventing the lock from being opened from the outside, consisting of a Ushaped wire bracket which can be snapped onto the door knob hub which acts as an anchor for the attachment. The closed end of the attachment is bent to form a claw for gripping the wings of the thumb knob and preventing the lock from being opened from the outside by a pass key or other device. It can be shifted on the lock to an inoperative position or pulled off entirely leaving the door unmarred.

United States Patent Moses 1 Jan. 28, 1975 [5 DOOR LOCK ATTACHMENT 3,585,827 6/l97l Dominquez 70/416 [76] Inventor: AdolphMoses, 8 E. 83rd St., New

Y k N Y 10028 Primary Examiner-Robert L. Wolfe Attorney, Agent, or Firm-Allison C. Collard [22] Filed: Oct. 2, 1973 [21] App]. No.: 402,681 [57] ABSTRACT A clamping attachment for a lock bolt thumb knob for [22] :J.S.CCII. preventing h lock from being Opened from the 0UP i 429 side, consisting of a U-shaped wire bracket which can l 1 le 0 care b 43 44 be snapped onto the door knob hub which acts as an 7 anchor for the attachment. The closed end of the attachment is bent to form a claw for gripping the wings [56] References C'ted of the thumb knob and preventing the lock from being UNITED STATES PATENTS opened from the outside by a pass key or other device. 994,285 6/1911 Sukeforth 70/430 it can be shifted on the lock to an inoperative position ,7 5, 3/1929 Healhl 70/430 or pulled off entirely leaving the door unmarred. 2,109,846 3/1938 Merrell 70/430 2,463,195 3/1949 Morgan 70/416 12 Claims, 6 Drawing Figures 1 DOOR LOCK ATTACHMENT This invention relates to a clamping attachment to a lock bolt thumb knob to prevent the lock from being include a bolt thumb knob usually located above the door handle or knob and on the room or inside of the door so that the room occupant can bolt or unbolt the door from the inside by rotating the thumb knob through a quarter of a revolution. However, even when the bolt is in a locked position, persons using pass keys, lock picking devices or cylinder wrenches, can force the bolt back into the lock, unlock and open the door. But if the thumb knob is restrained from rotating, it is impossible from the outside for the bolt to be returned to its unlocked or inoperative position less the lock mechanism is broken. In that event, there will be evidence of forcible entry and grounds for collecting burglary insurance that might be in force.

- The present invention provides a simple, inexpensive device capable of constraining the thumb knob of a lock against rotation after the device has been detachably slipped or snapped onto the lock and placed in the operative position. The device can be shifted on the lock to an inoperative position or it may be removed by hand for use elsewhere.

It is therefore an object according the present invention to provide a clamping device for optionally constraining the rotation of a thumb knob so as to prevent the opening of a bolt type lock from the outside.

Other objects of the present invention are to provide for a thumb knob, a clamp which is cheap, reliable, requires no skill, no screws, drilling or tools to apply, does not mar the door, and which adapts itself to various lock dimensions.

Other objects and features of the present invention will become apparent from the following detailed description considered inconnection with the accompanying drawing which discloses the embodiment of the invention. It is to be understood that the drawing is designed for the purpose of illustration only and not as a definition of the limits of the invention.

In the drawing wherein similar reference characters denote similar elements throughout the several views:

FIG. 1 is an elevation or inside view of a section of a door in which a bolt type lock has been installed and the locking device 10 is shown placed in its inoperative position on the lock, and with the thumb knob 13 in the bolt with drawn position.

FIG. 2 is-a side view of FIG. 1.

FIG. 3 shows the thumb knob 13 in the bolt extended position and with the device 10 in its operative position embracing boththe thumb knob 13 and the door knob hub 14.

FIG. 4 is a cross sectional view taken along section line 4-'-4 of FIG. 3.

FIG. 5 is a side view of FIG. 3.

FIG. 6 is a truncated variation of the device shown in FIG. 1 but showing an alternate form 26 and 33 of the ends 17 of the device.

The front elevation or view of the locking device 10 is shown in FIG. 1. It is preferably formed from spring steel wire, which has a circular cross section. Its top end is formed into an inverted V 20, shown in FIGS. 2 and 5. There are two inverted Vs joined at one end by a U or V shaped portion 21, as shown in FIGS. 1 and 3. Referring to FIG. 2, the ends 25 of the inverted Vs 20 extend downward and at 28, are bent inward towards the center line of the inverted Vs 20. Further down at 37, the legs are bent away from the center line of the inverted Vs 20. FIGS. 1 and 3 show these legs bent at 29 inward substantially at an angle to the center line of U21. This makes the legs 19 concave at 29 relative to the center line of the U 21. Farther down, the legs 19 are successively convex at 30, concave at 18, and again convex at 31, ending with hemispherical ends 17 as shown in FIGS. 1, 2, 3 and 5, or with flat ends 26, formed into an eye or. loop 33 as shown in FIG. 6.

Referring to FIGS. 1 and 2, with the device 10 in its inoperative position and the thumb knob 13 in the bolt withdrawn position, locking device 10 has been placed over the thumb knob 13 of a conventional bolt type door lock, which has a door knob 12, connected by its hub 14 through cover plate 15 to the internal mechanism of an ordinary lock. The device 10 is pushed down on the hub 14, causing the ends 17 or modified ends 33 to be sprung apart until portions 18 embrace the hub 14, which supports the device 10 in this inoperative position. It should be noted that the door knob 12 would not be turned unless the device is in the inoperative position where the ends 17, as shown in FIG. 2, would clear the fingers grasping the door knob 12. The center of gravity of the device being nearer the door than the points of contact of hub 14 with the element 18 of the device 10, the device 10 leans against the thumb knob plate 32. Thespring grip of the concave section 18 of legs 19 on the hub 14 helps to maintain the device 10 in the inoperative position shown in FIGS. 1 and 2.

FIG. 1 shows that in the inoperative position, the device 10 contacts the hub 14 at points 39 above the center of the hub 14. The reaction of hub 14 against the device 10 at points 39 will therefore have an upward component which is shown in FIG. 2 by the arrow at 39. There are also contacts with the hub 14 shown in FIG. 1 at points 34 below the center of hub 14. The reaction of hub 14 against the device 10 at points 34 will therefore have a downward component, which is shown in FIG. 2 by the arrow at point 34. It will be apparent from FIG. 2 that these component forces produce a couple urging the device 10 to rotate clockwise, thus urging the hooks 20 towards the plate 32. The device 10 will function without this feature but it makes for a smoother actuation of the lock by a key when the device 10 is in its inoperative position. With the device 10 in this inoperative position, the thumb knob 13 may be given a quarter turn bringing it to a horizontal position. When the device 10 is in this inoperative position, the lock may also be operated from the outside by a key. The thumb knob 13 may be turned from the inside back to the vertical position to unlock the door while the device 10 is in this inoperative position.

FIG. 3 shows the thumb knob 13 rotated anticlockwise to a horizontal or nearly horizontal position which extends the bolt that locks the door. The sections 7 22 of legs 19 are bent inward towards the center line also prevents the device 10 from being jarred to an inoperative position.

Any attempt to unlock the door from the outside would result in urging the thumb knob 13 to turn counterclockwise. But the thumb knob 13 cannot turn farther counter clockwise because it is embraced or trapped by the sections 27 and 25 of the two inverted V hooks 20, which are sufficiently stiff to resist the forces that may be exerted against them by the thumb knob 13. These forces are minimized by sections 25 being as far as practicable from the axis of the thumb 13. Having the section 27 as near as practicable to the axis of thumb knob 13 minimizes the rotation of the thumb knob 13. It should be borne in mind that the torque at the thumb knob 13 is only a fraction of the torque on the lock cylinder.

It should be noted that the hooks 20 and bracket 10 cannot rotate about the axis of the thumb knob 13 since any torque exerted by the thumb knob 13 on the hooks 20 would urge one of the legs 19 against the hub 14, which prevents rotation of the device 10. The reaction force of the hub 14 against 22 on leg 19 has a down component which pulls the hooks 20 more firmly down on the thumb knob 13. Thus, while the bracket 10 is in its operative position shown in FIGS. 3, 4 and 5, the lock cannot be operated from the outside.

Note that the device 10 as shown in FIG. 3 is symmetrical and therefore will function equally well on locks where clockwise rotation of the thumb knob 13 opens the lock.

In brief, the device 10 may be placed in its inoperative position shown in FIGS. 1 and 2 by simply pushing it down over the thumb knob 13 and hub 14 until it is detained by detent l8, contacting hub 14. From this inoperative position it may be shifted to its operative position shown in'FIGS. 3, 4, and 5 by pushing it down as far as it will go where it will be detained and urged downward by detent 22 contacting hub 14. The device when it is in its inoperative position shown in FIGS. 1 and 2 may be removed by pulling upward on hooks 20.

When the device is in the operative position shown in FIGS. 3 and 5, it may be removed by first pushing upward with a finger on end 17, to position the device in its inoperative position, shown in FIGS. 1 and 2, from which it may be removed as explained above.

If it is known that the thumb knob 13 is going to be handled many times before the attachment is placed in its operative position as in FIG. 3, the attachment 10 may while in its inoperative position as in FIG. 1, be pulled by the hooks away from the door 11 until the attachment l0 clears the thumb knob 13, whereupon the attachment 10 may be rotated on half a revolution on the hub 14 and left hanging down from the hub 14, thereby making it more convenient to turn the thumb knob 13 by hand and insuring smoother operation of the lock by its key.

Referring to FIG. 6, the bracket 10 as shown in FIG. 3 does not have the concave detent portion 18 but starting at point 30 has its ends curled outward to form an eye. This makes unnecessary the machining operation on the ends 17 and provides ends which are easier on pocket linings and are more comfortable to handle. The truncated embodiment of the present invention is intended to be slid upward off the lock when the device is to be inoperative. It may then be inverted and pushed upward on hub 14 and left hanging downward therefrom or it may be carried away.

Note that this shortened embodiment, which does not include concave element 18, does not need to have bends which start at 28 and 37, as shown in FIG. 2.

What is claimed is:

1. A snap on and off attachment for optionally restraining rotation of the thumb knob of a lock having a door knob comprising:

a bracket having at one end means to optionally embrace the thumb knob consisting of a pair of siamese inverted substantially V-shaped hooks straddling the thumb knob axis to restrain the rotation relative to the bracket; and

at the opposite end means for demountably embracing the door knob hub consisting of a pair of spring legs so as to anchor the bracket against rotation about the thumb knob axis.

2. The attachment as recited in claim 1, wherein the hooks can adapt themselves to a range of thumb knob dimensions.

3. The attachment as recited in claim 1, wherein one or both of said legs has a concave portion located with respect to the hooks so that when the concave portion is aligned with the door knob hub, the hooks are held out of engagement with the thumb knob wings but may be engaged with the wings by pushing the bracket down.

4. The attachment is recited in claim 3, wherein the upper contact point of said concave portion with the door knob hub is farther from the door than the lower contact point of said concave portion with the door knob hub.

5. The attachment is recited in claim 1, wherein one or both of said spring legs has a concave or angled portion located so that when the bracket is pushed down to engage the thumb knob wings, said angled portion contacts the door knob hub below its axis, thus urging the hooks to grip the wings and to resist the hooks from being jarred out of engagement with the wings.

6. The attachment as recited in claim 5, wherein said angled portion is of sufficient length to accommodate the desired range of door knob to thumb knob center distances and the desired range of thumb knob dimensions.

7. The attachment as recited in claim 1, wherein each of said legs just below the lowest thumb knob gripping tip is bent towards the centerline of the V portions of the hooks.

8. The attachment as recited in claim I, wherein each of said leg ends are rounded or hemispherical.

9. The attachment as recited in claim 1, wherein the end of each of said legs is curled outward to form an eye.

10. The attachment as recited in claim 1. wherein each of said legs has an end portion which is spread outward.

11. The attachment as recited in claim 1, wherein said bracket is formed from a single piece of material.

12. The attachment as recited in claim 5, wherein the legs are coiled or flared outward just below the said angled portion and then terminated. 

1. A snap on and off attachment for optionally restraining rotation of the thumb knob of a lock having a door knob comprising: a bracket having at one end means to optionally embrace the thumb knob consisting of a pair of siamese inverted substantially V-shaped hooks straddling the thumb knob axis to restrain the rotation relative to the bracket; and at the opposite end means for demountably embracing the door knob hub consisting of a pair of spring legs so as to anchoR the bracket against rotation about the thumb knob axis.
 2. The attachment as recited in claim 1, wherein the hooks can adapt themselves to a range of thumb knob dimensions.
 3. The attachment as recited in claim 1, wherein one or both of said legs has a concave portion located with respect to the hooks so that when the concave portion is aligned with the door knob hub, the hooks are held out of engagement with the thumb knob wings but may be engaged with the wings by pushing the bracket down.
 4. The attachment is recited in claim 3, wherein the upper contact point of said concave portion with the door knob hub is farther from the door than the lower contact point of said concave portion with the door knob hub.
 5. The attachment is recited in claim 1, wherein one or both of said spring legs has a concave or angled portion located so that when the bracket is pushed down to engage the thumb knob wings, said angled portion contacts the door knob hub below its axis, thus urging the hooks to grip the wings and to resist the hooks from being jarred out of engagement with the wings.
 6. The attachment as recited in claim 5, wherein said angled portion is of sufficient length to accommodate the desired range of door knob to thumb knob center distances and the desired range of thumb knob dimensions.
 7. The attachment as recited in claim 1, wherein each of said legs just below the lowest thumb knob gripping tip is bent towards the centerline of the V portions of the hooks.
 8. The attachment as recited in claim 1, wherein each of said leg ends are rounded or hemispherical.
 9. The attachment as recited in claim 1, wherein the end of each of said legs is curled outward to form an eye.
 10. The attachment as recited in claim 1, wherein each of said legs has an end portion which is spread outward.
 11. The attachment as recited in claim 1, wherein said bracket is formed from a single piece of material.
 12. The attachment as recited in claim 5, wherein the legs are coiled or flared outward just below the said angled portion and then terminated. 